The invention relates generally to orthodontic and dental devices and systems and methods for making same. More specifically, the invention relates to guide apparatus, systems and methods for making tooth positioning appliances.
Orthodontic treatments involve repositioning misaligned teeth and improving bite configurations for improved cosmetic appearance and dental function. Repositioning teeth is accomplished by applying controlled forces to the teeth over an extended period of time. This is conventionally accomplished by wearing what are commonly referred to as “braces.” Braces comprise a variety of appliances such as brackets, bands, archwires, ligatures, and O-rings. The brackets and bands are bonded to the patient's teeth using a suitable material, such as dental adhesive. Once the adhesive has set, the archwire is attached to the brackets by way of slots in the brackets. The archwire links the brackets together and exerts forces on them to move the teeth over time. Twisted wires or elastomeric O-rings are commonly used to reinforce attachment of the archwire to the brackets. Attachment of the archwire to the brackets is known in the art of orthodontia as “ligation” and wires used in this procedure are called “ligatures.” The elastomeric O-rings are called “ties.”
After the archwire is in place, periodic meetings with the orthodontist are required, during which the patient's braces are adjusted. Such adjustments include installing and bending different archwires having different force-inducing properties and replacing or tightening existing ligatures. Between orthodontic appointments, the patient may be required to wear supplemental appliances, such as elastic bands or headgear, to supply additional or extraoral forces.
Although conventional braces are effective, they are often a tedious and time consuming process requiring many visits to the orthodontist's office. Moreover, from a patient's perspective, they are unsightly and uncomfortable. Moreover, the archwire and ligatures which connect the brackets in a continuous network make brushing, flossing between the teeth and other dental hygiene procedures challenging, possibly contributing to the development of gingivitis, enamel decalcification and/or decay. Consequently, alternative orthodontic treatments are needed. In particular, it would be desirable to use appliances which can be removed by the patient during daily dental hygiene routines, while participating in athletic activities, or for cosmetic purposes.
A particularly promising approach relies on the use of elastic positioning appliances for realigning teeth. Such appliances comprise a thin shell of elastic material that generally conforms to a patient's teeth but is slightly out of alignment with the initial tooth configuration. Placement of the elastic positioner over the teeth applies controlled forces in specific locations to gradually move the teeth into the new configuration. Repetition of this process with successive appliances comprising new configurations eventually moves the teeth through a series of intermediate configurations to a final desired configuration. Various systems, methods and apparatus for moving teeth with such appliances are described in numerous patents assigned to the assignee of the present application, such as U.S. Pat. Nos. 5,975,893; 6,183,248; 6,210,162; 6,217,325; 6,227,851; 6,227,850; 6,299,440; 6,309,215; 6,318,994; 6,371,761; 6,386,864; 6,386,878; 6,390,812; D457,638S; U.S. Pat. Nos. 6,394,801; 6,398,548; 6,406,292; 6,409,504; 6,450,807; 6,454,565; 6,457,972; 6,463,344; 6,471,511; 6,485,298; 6,488,499; 6,497,574; 6,499,997; 6,514,074; 6,524,101; 6,554,611; 6,572,372; 6,582,227; 6,582,229; 6,602,070; 6,607,382; 6,621,491; 6,626,666; 6,629,840; 6,633,789; 6,665,570; 6,682,346; 6,685,469; 6,685,470; 6,688,886; 6,699,037; 6,705,861; 6,705,863; 6,722,880; 6,726,478; 6,729,876; 6,761,560; 6,767,208; 6,783,360; 6,783,604; 6,786,721; 6,790,035; 6,802,713; 6,814,574; and 6,830,450; all of which are incorporated herein by reference and are referred to below as “the incorporated references.”
One method for manufacturing tooth positioning appliances, described more fully in the incorporated references, involves taking an impression of the patient's teeth, scanning the impression to provide an initial digital data set representing the teeth in their pre-treatment positions, manipulating the digital data to provide intermediate and final digital data sets representing treatment positions for moving the teeth, using the data sets to create positive molds of the appliances, and making appliances as negatives of the positive molds. Variations of such methods may involve directly scanning the patient's teeth, creating a solid model of the teeth and scanning the model, manipulating such a solid model, and many other variations described in the incorporated references. In some techniques, the positive molds are created using a rapid prototyping method, such as stereolithography. Appliances are then made by thermoforming or otherwise forming a plastic material over the molds and separating and trimming the plastic to produce the appliances. Although such manufacturing methods work quite well and are often optimal for producing tooth moving appliances, alternative manufacturing methods that may be more efficient, less expensive, require less material or manual input and the like are continually being sought.
One alternative method for making tooth moving appliances involves first forming a physical, three-dimensional model of the patient's upper or lower teeth. One or more of the teeth are then separated from the model, such as by cutting, and moved to a desired intermediate or final position on the model. The moved tooth or teeth are then secured in place on the model in its/their new positions, and a plastic or similar material is formed over the model with the moved teeth. The formed plastic is then trimmed and removed from the model to produce an appliance. One or more teeth can then be separated from the model again, moved to new positions and secured, and a second appliance may be formed over the model. This can be repeated to form as many appliances, or sets of upper and lower appliances, as desired. In an alternative version, the model may be manipulated to a first configuration, a copy of the model may be made, and an appliance may be made from the copy. The original model may be moved to a second configuration, a copy made, and a second appliance made, and so on. One advantage of such methods is that an inexpensive material, such as dental plaster, may be used to form the model (or models) of the patient's teeth, and such a material and process will typically be less expensive than certain rapid prototyping processes, such as stereolithography, which produces a separate positive mold of hardened resin for each appliance to be manufactured. Such methods of manually manipulating a solid model have inherent drawbacks, however, in that the teeth separated from the model are placed in their new positions on the model by hand and by approximation. These manipulations require a great deal of skill and experience, which may lead to suboptimal results for the patient and may also make mass production of appliances very difficult, if not impossible.
Therefore, it would be desirable to develop alternative methods, systems and apparatus for manipulating physical tooth models and for making tooth moving appliances. Such methods, systems and apparatus would ideally provide for precision in model manipulation and, thus, in production of appliances. Such methods, systems and apparatus would also ideally provide for appliance manufacture at reduced cost as compared to currently available, more precise methods. For example, such methods, systems and apparatus may require less material or human input. At least some of these objectives will be met by the present invention.